Genetics of somatotype and physical fitness in children and adolescents.

OBJECTIVES: To analyze the influence of genetic and environmental factors on the variation in somatotype, physical fitness, and their mutual associations. METHODS: Twins from 214 pairs (87 monozygotic) of the Autonomous Region of Madeira, Portugal, from 3 to 18 years of age (51% girls) were assessed in anthropometry and physical fitness tests. We estimated endomorphy, mesomorphy, and ectomorphy based on anthropometric measures and physical fitness using the Eurofit test battery. Two age categories were analyzed: children (3-11 years) and adolescents (12-18 years). Genetic and environmental variations were estimated using quantitative genetic twin modeling. RESULTS: No genetic sex differences were found, thus boys and girls were pooled in all genetic analyses. Heritability estimates were high for somatotype (a2  = 0.80-0.93), physical fitness traits (a2  = 0.67-0.83), and largely similar in children and adolescents. Positive correlations were found for ectomorphy with motor ability and cardiorespiratory endurance as well as for endomorphy and mesomorphy with muscular strength (r = 0.25-0.37). In contrast, negative associations were found for ectomorphy with muscular strength, as well as for endomorphy and mesomorphy with motor ability and cardiorespiratory endurance (-0.46 to -0.26). Twin modeling indicated that these associations were explained mostly by genetic factors in common to the two associated traits (84% or more). CONCLUSIONS: Associations between somatotype and physical fitness tests are mainly explained by common genetic background in children and adolescents. Therefore, interventions in youth should consider that a child's performance in physical fitness tests partly reflects their inherited physique.

Stability of potential renal acid load.

AIM: The potential renal acid load (PRAL) has been described in relation to different health outcomes. Outcomes over time and conclusions made are often based on baseline dietary intake values. However, to study reliable long-term associations, parameters calculated based on dietary intake data, such as PRAL, must be stable over time. Therefore, the aim of the present study was to assess the stability of PRAL and its components over a 10-year time period. METHODS: PRAL values of three-day dietary intake data from 197 women and 373 men on two assessment moments (2002-2004 and 2012-2014) were calculated. Pearson correlation and intra-class correlation coefficients were used for assessing the stability of PRAL and its components. Level of agreement between the two assessment moments was estimated after splitting up subjects in quintiles of PRAL, calculating kappa values and changes of quintiles over time. RESULTS: No significant differences in mean PRAL over time were found. Stability of PRAL and its components was low. Poor agreement between the first and second assessment was shown by low kappa values and change of most of the subjects to an adjacent and non-adjacent quintile after 10 years. CONCLUSIONS: Based on nutrition assessments carried out using three-day dietary records, stability of PRAL over a 10-year time period could not be confirmed, even though no significant difference between mean PRAL and its components over time was found. Therefore, interpretation of longitudinal outcomes based on PRAL and its component calculated at baseline should be interpreted with caution.

A 10-year longitudinal study on the associations between changes in plant-based diet indices, anthropometric parameters and blood lipids in a Flemish adult population.

AIM: Plant-based diets are recommended in the context of environmental sustainability and health. Since not all plant foods can be considered beneficial, a distinction needs to be made between healthful and unhealthful plant foods. The aim of this study was to investigate longitudinal associations between changes in an overall plant-based diet index, a healthful plant-based diet index and an unhealthful plant-based diet index, with changes in anthropometrics and blood lipids as indicators of morphological and metabolic fitness, respectively. METHODS: A 3-day dietary record was completed by 650 Flemish adults (420 men, 230 women) in 2002-2004 and 2012-2014. Three plant-based diet indices were calculated based on quintile scores regarding the intake of animal- or plant-based food items. Associations between 10-year changes in diet indices and changes in anthropometrics and blood lipids were tested using multivariate linear regression. RESULTS: Plant-based diet indices did not differ over time. Using the unadjusted model, few significant associations were found between changes in diet indices and changes in anthropometrics and blood lipids. However, these relationships disappeared after adjusting for confounding. In women, a positive association was found between changes in overall plant-based diet index and changes in body mass index in the adjusted model. CONCLUSIONS: Index values did not differ over time and few longitudinal associations were found.

Low 10-year reproducibility of glycaemic index and glycaemic load in a prospective cohort study.

When relating glycaemic index (GI) and glycaemic load (GL) to health outcomes, many prospective cohort studies assess the nutritional exposure only once in time, that is, at the start of the study, presuming a stability in nutritional consumption during the course of the study. The aim of this study is to investigate the reproducibility of GI and GL. This is a prospective cohort study in which 562 middle-aged Belgian adults noted all foods and drinks consumed during 3 d in 2002 and 2012. GI and GL were calculated after reference tables. The Pearson correlation coefficients between 2002 and 2012 were 0·27 for GI and 0·41 for GL. For GI, 33 % of the participants remained in the same quintile between 2002 and 2012, whereas 31 % moved to a non-adjacent quintile. For GL, this was 34 and 28 %, respectively. The lowest and the highest quintiles of GI were the most stable, with 40 and 44 % of the participants staying in the same quintile. This was only 22 % for the fourth quintile. The same tendency was present for GL - that is, the most extreme quintiles were the most stable. This study shows 10-year correlation coefficients for GI and GL below 0·50. Multiple nutritional assessments and limiting the analysis to the extreme quintiles of GI and GL will limit a possible misclassification in the prospective cohort studies owing to the low reproducibility.

Year-round effects of a four-week randomized controlled trial using different types of feedback on employees' physical activity.

BACKGROUND: This follow-up study investigated the year-round effects of a four-week randomized controlled trial using different types of feedback on employees' physical activity, including a need-supportive coach intervention. METHODS: Participants (n = 227) were randomly assigned to a Minimal Intervention Group (MIG; no feedback), a Pedometer Group (PG; feedback on daily steps only), a Display Group (DG; feedback on daily steps, on daily moderate-to-vigorous physical activity [MVPA] and on total energy expenditure [EE]), or a Coaching Group (CoachG; same as DG with need supportive coaching). Daily physical activity level (PAL; Metabolic Equivalent of Task [MET]), number of daily steps, daily minutes of moderate to vigorous physical activity (MVPA), active daily EE (EE > 3 METs) and total daily EE were measured at five time points: before the start of the 4-week intervention, one week after the intervention, and 3, 6, and 12 months after the intervention. RESULTS: For minutes of MVPA, MIG showed higher mean change scores compared with the DG. For steps and daily minutes of MVPA, significantly lower mean change scores emerged for MIG compared with the PG. Participants of the CoachG showed significantly higher change scores in PAL, steps, minutes of MVPA, active EE, total EE compared with the MIG. As hypothesized, participants of the CoachG had significantly higher mean change scores in PAL and total EE compared with groups that only received feedback. However, no significant differences were found for steps, minutes of MVPA and active EE between CoachG and PG. CONCLUSIONS: Receiving additional need-supportive coaching resulted in a higher PAL and active EE compared with measurement (display) feedback only. These findings suggest to combine feedback on physical activity with personal coaching in order to facilitate long-term behavioral change. When it comes to increasing steps, minutes of MVPA or active EE, a pedometer constitutes a sufficient tool. TRIAL REGISTRATION: Clinical Trails.gov NCT01432327 . Date registered: 12 September 2011.

Intensity-Specific Differential Leukocyte DNA Methylation in Physical (In)Activity: An Exploratory Approach.

The aim of this exploratory study was to investigate how sedentary behavior (SB) and physical activity (PA) influence DNA methylation at a global, gene-specific, and health-related pathway level. SB, light PA (LPA), and moderate-to-vigorous PA (MVPA) were assessed objectively for 41 Flemish men using the SenseWear Pro 3 Armband. CpG site-specific methylation in leukocytes was determined using the Illumina HumanMethylation 450 BeadChip. Correlations were calculated between time spent on the three PA intensity levels and global DNA methylation, using a z-score-based method to determine global DNA methylation levels. To determine whether CpG site-specific methylation can be predicted by these three PA intensity levels, linear regression analyses were performed. Based on the significantly associated CpG sites at α = 0.005, lists were created including all genes with a promoter region overlapping these CpG sites. A biological pathway analysis determined to what extent these genes are overrepresented within several pathways. No significant associations were observed between global DNA methylation and SB (r = 0.084), LPA (r = -0.168), or MVPA (r = -0.125), although the direction of the correlation coefficients is opposite to what is generally reported in literature. SB has a different impact on global and gene-specific methylation than PA, but also LPA and MVPA affect separate genes and pathways. Furthermore, the function of a pathway seems to determine its association with SB, LPA, or MVPA. Multiple PA intensity levels, including SB, should be taken into account in future studies investigating the effect of physical (in)activity on human health through epigenetic mechanisms.

Motor performance, body fatness and environmental factors in preschool children.

The first aim of this study was to investigate the relationship between motor performance and body fatness among 3- to 5-year-old children. The second aim was to assess whether this relationship works similarly for boys and girls. We also investigated whether socioeconomic status (SES) and geographical area when children are aged 3 years old predicts the motor performance of 4 and 5-yr-old children. Motor performance was assessed through the Preschool Test Battery, while body fatness was estimated through body mass index (BMI). SES and geographical area were assessed via parent proxy-report questionnaires. BMI was negatively associated with standing long jump. The association of BMI and motor performance was not statistically different for boys and girls. Children from low SES performed better than high SES peers in tennis ball throw for distance. Rural children were better performers than urban peers in standing long jump. Rural area at baseline was also predictor of standing long jump and tennis ball throw for distance at time 1 and 2. In conclusion, BMI had a negative association with standing long jump and the relationship of BMI with all motor tests was similar for boys and girls. SES and rural area were predictors of motor performance.

Ten-year change in sedentary behaviour, moderate-to-vigorous physical activity, cardiorespiratory fitness and cardiometabolic risk: independent associations and mediation analysis.

BACKGROUND: We aimed to study the independent associations of 10-year change in sedentary behaviour (SB), moderate-to-vigorous physical activity (MVPA) and objectively measured cardiorespiratory fitness (CRF), with concurrent change in clustered cardiometabolic risk and its individual components (waist circumference, fasting glucose, high-density lipoprotein (HDL) cholesterol, triglycerides and blood pressure). We also determined whether associations were mediated by change in CRF (for SB and MVPA), waist circumference (for SB, MVPA and CRF) and dietary intake (for SB). METHODS: A population-based sample of 425 adults (age (mean±SD) 55.83±9.40; 65% men) was followed prospectively for 9.62±0.52 years. Participants self-reported SB and MVPA and performed a maximal cycle ergometer test to estimate peak oxygen uptake at baseline (2002-2004) and follow-up (2012-2014). Multiple linear regression and the product of coefficients method were used to examine independent associations and mediation effects, respectively. RESULTS: Greater increase in SB was associated with more detrimental change in clustered cardiometabolic risk, waist circumference, HDL cholesterol and triglycerides, independently of change in MVPA. Greater decrease in MVPA was associated with greater decrease in HDL cholesterol and increase in clustered cardiometabolic risk, waist circumference and fasting glucose, independent of change in SB. Greater decrease in CRF was associated with more detrimental change in clustered cardiometabolic risk and all individual components. Change in CRF mediated the associations of change in SB and MVPA with change in clustered cardiometabolic risk, waist circumference and, only for MVPA, HDL cholesterol. Change in waist circumference mediated the associations between change in CRF and change in clustered cardiometabolic risk, fasting glucose, HDL cholesterol and triglycerides. CONCLUSIONS: A combination of decreasing SB and increasing MVPA, resulting in positive change in CRF, is likely to be most beneficial towards cardiometabolic health.

Substituting Sedentary Time With Light and Moderate to Vigorous Physical Activity is Associated With Better Cardiometabolic Health.

BACKGROUND: The purpose of the current study was to apply a more novel approach to systematically examine (1) associations of clustered cardiometabolic risk and cardiometabolic risk factors and (2) theoretical substitution of sedentary time with either sleep, light physical activity (LPA), or moderate to vigorous physical activity (MVPA) and substituting LPA with MVPA. METHODS: Physical activity and sleep were objectively measured in 410 Flemish adults [55.5 (9.6) y, 64% men] with a SenseWear Pro 3 Armband. Cardiometabolic risk factors (obesity, hyperglycemia, dyslipidemia, and hypertension) and cardiorespiratory fitness were objectively measured. Isotemporal substitution analyses were performed to assess the associations between substituting time from a potentially negative behavior into another potentially positive behavior. RESULTS: Theoretical substitution of sedentary time with MVPA was associated with decreased clustered cardiometabolic risk, b = -0.06 (-0.08 to -0.04), and substituting LPA with MVPA was associated with a decrease in clustered cardiometabolic risk, b = -0.08 (-0.11 to -0.04). Substituting sedentary time with LPA or sleep improved high-density lipoprotein-cholesterol, systolic and diastolic blood pressures, and waist circumference. CONCLUSION: Theoretical replacement of sedentary time with either sleep, LPA, or MVPA was positively associated with improved cardiometabolic risk factor status. Interventions for increasing cardiometabolic health can focus on replacing sedentary time with either sleep, LPA, or MVPA depending on the risk parameters that need to be targeted.

Biological and environmental determinants of 12-minute run performance in youth.

BACKGROUND: The 12-minute run is a commonly used indicator of cardiorespiratory fitness in youth. Variation in growth and maturity status as potential correlates of test performance has not been systematically addressed. AIM: To evaluate biological and environmental determinants of 12-minute run performance in Portuguese youth aged 7-17 years. SUBJECTS AND METHODS: Mixed-longitudinal samples of 187 boys and 142 girls were surveyed in 1996, 1997 and 1998. The 12-minute run was the indicator of cardiorespiratory fitness. Height, body mass and five skinfolds were measured and skeletal maturity was assessed. Physical activity, socioeconomic status and area of residence were obtained with a questionnaire. Multi-level modelling was used for the analysis. RESULTS: Chronological age and sum of five skinfolds were significant predictors of 12-minute run performance. Older boys and girls ran longer distances than younger peers, while high levels of subcutaneous fat were associated with shorter running distances. Rural boys were more proficient in the 12-minute run than urban peers. Skeletal maturity, height, body mass index, physical activity and socioeconomic status were not significant predictors of 12-minute run performances. CONCLUSIONS: Age and sum of skinfolds in both sexes and rural residence in boys are significant predictors of 12-minute run performance in Portuguese youth.

The Genetic Background of Metabolic Trait Clusters in Children and Adolescents.

BACKGROUND: It is well known that metabolic risk factors of cardiovascular diseases are correlated, but the background of this clustering in children is more poorly known than in adults. Thus, we studied the contribution of genetic and environmental factors to the clustering of metabolic traits in childhood and adolescence. DATA AND METHODS: Nine metabolic traits were measured in 214 complete twin pairs aged 3-18 years in the Autonomous Region of Madeira, Portugal, in 2007 and 2008. The variation of and covariations between the traits were decomposed into genetic and environmental components by using classical genetic twin modeling. RESULTS: A model, including additive genetic and environmental factors unique for each twin individual, explained the variation of metabolic factors well. Under this model, the heritability estimates varied from 0.47 (systolic blood pressure in children under 12 years of age) to 0.91 (high-density lipoprotein [HDL] cholesterol in adolescents 12 years of age or older). The most systematic correlations were found between adiposity (body mass index and waist circumference) and blood lipids (HDL cholesterol, low-density lipoprotein cholesterol, and triglycerides), as well as blood pressure. These correlations were mainly explained by common genetic factors. CONCLUSIONS: Our results suggest that obesity, in particular, is behind the clustering of metabolic factors in children and adolescents. Both general and abdominal obesity partly share the same genetic background as blood lipids and blood pressure. Obesity prevention early in childhood is important in reducing the risk of metabolic diseases in adulthood.

Limited potential of genetic predisposition scores to predict muscle mass and strength performance in Flemish Caucasians between 19 and 73 years of age.

Since both muscle mass and strength performance are polygenic in nature, the current study compared four genetic predisposition scores (GPS) in their ability to predict these phenotypes. Data were gathered within the framework of the first-generation Flemish Policy Research Centre "Sport, Physical Activity and Health" (2002-2004). Results are based on muscle characteristics data of 565 Flemish Caucasians (19-73 yr, 365 men). Skeletal muscle mass was determined from bioelectrical impedance. The Biodex dynamometer was used to measure isometric (PTstatic120°) and isokinetic strength (PTdynamic60° and PTdynamic240°), ballistic movement speed (S20%), and muscular endurance (Work) of the knee extensors. Genotyping was done for 153 gene variants, selected on the basis of a literature search and the expression quantitative trait loci of selected genes. Four GPS were designed: a total GPS (based on the sum of all 153 variants, each favorable allele = score 1), a data-driven and weighted GPS [respectively, the sum of favorable alleles of those variants with significant b-coefficients in stepwise regression (GPSdd), and the sum of these variants weighted with their respective partial r2 (GPSw)], and an elastic net GPS (based on the variants that were selected by an elastic net regularization; GPSen). It was found that four different models for a GPS were able to significantly predict up to ~7% of the variance in strength performance. GPSen made the best prediction of SMM and Work. However, this was not the case for the remaining strength performance parameters, where best predictions were made by GPSdd and GPSw.

Associations between physical activity and health-related fitness - volume versus pattern.

Approximately 3.2 million people die of non-communicable diseases (NCD) each year due to insufficient physical activity. Physical activity guidelines are possibly perceived as too demanding and might thus pose a barrier. We addressed the question if a more stable physical activity pattern is associated with higher levels of health-related fitness than one with high and low intensities, regardless of the physical activity level (PAL). Physical activity was objectively measured in 296 men and women (53.7 ± 8.94 years) with the SenseWear Pro Armband®. Using this data, the PAL and a Gini index were calculated to report the physical activity pattern. Health-related fitness was expressed as a fitness index. PAL was weakly correlated to health-related fitness (r = 0.38, P < .0001). The Gini index was also weakly correlated to the fitness index (r = 0.23, P < .0001). Results of the ANCOVA showed that participants in the first quartile of PAL always scored significantly lower for health-related fitness than participants in quartile four, after adjustment for the Gini index. These results suggest that as long as the volume of physical activity is high, health-related fitness will be high as well, independent of the physical activity pattern or variability in intensities throughout the day.

Assessment of sugar-sweetened beverage consumption and weight change: a prospective cohort study.

BACKGROUND: In prospective studies, sugar-sweetened beverages (SSB) have been associated with weight increase. However, most prospective studies examine changes in body weight over time according to amounts of SSB intake at baseline, generally without considering changes over time in SSB, energy intake and physical activity. The objective of the present study was to examine how SSB intakes influence changes in weight, according to the way SSB intakes are analysed. METHODS: For a prospective cohort study with two nutritional assessments in time, 46 Flemish municipalities were selected by clustered random sampling. Within these municipalities, a random sample of men and women between 18 and 75 years of age was selected and invited to participate. In total, 562 middle-aged Belgian adults were tested in 2002 and 2012 for the same anthropometric, lifestyle, nutrition and physical activity parameters. The main outcome measured were weight changes from 2002 to 2012 were analysed according to various ways to parametrise SSB intakes in 2002 and changes in SSB, energy intake, and physical activity from 2002 to 2012. RESULTS: In a multivariable model including age, sex, the best predictors of weight changes were the weight at baseline (P < 0.001), then the change in energy intake (p = 0.068). No association was found with SSB intake at baseline (P = 0.267) and the change in SSB intake (P = 0.130). CONCLUSIONS: Results of prospective studies on SSB intake and body weight depend much on the way SSB intakes are analysed, and on the inclusion of changes in energy intake and physical activity in analyses.

Independent Associations between Sedentary Time, Moderate-To-Vigorous Physical Activity, Cardiorespiratory Fitness and Cardio-Metabolic Health: A Cross-Sectional Study.

We aimed to study the independent associations of sedentary time (ST), moderate-to-vigorous physical activity (MVPA), and objectively measured cardiorespiratory fitness (CRF) with clustered cardio-metabolic risk and its individual components (waist circumference, fasting glucose, HDL-cholesterol, triglycerides and blood pressure). We also investigated whether any associations between MVPA or ST and clustered cardio-metabolic risk were mediated by CRF. MVPA, ST, CRF and individual cardio-metabolic components were measured in a population-based sample of 341 adults (age 53.8 ± 8.9 years; 61% men) between 2012 and 2014. MVPA and ST were measured with the SenseWear pro 3 Armband and CRF was measured with a maximal exercise test. Multiple linear regression models and the product of coefficients method were used to examine independent associations and mediation effects, respectively. Results showed that low MVPA and low CRF were associated with a higher clustered cardio-metabolic risk (ß = -0.26 and ß = -0.43, both p<0.001, respectively). CRF explained 73% of the variance in the association between MVPA and clustered cardio-metabolic risk and attenuated this association to non-significance. After mutual adjustment for MVPA and ST, CRF was the most important risk factor for a higher clustered cardio-metabolic risk (ß = -0.39, p<0.001). In conclusion, because of the mediating role of CRF, lifestyle-interventions need to be feasible yet challenging enough to lead to increases in CRF to improve someone's cardio-metabolic health.

Health Policy Development in Flemish Small-Sized Municipalities: A Real-World Intervention.

BACKGROUND: A health promotion institute developed an intervention to support small-sized municipalities (<15,000 citizens; n = 167) in their development of a local health policy. OBJECTIVES: To (1) find out which municipalities showed interest to participate and (2) assess the intervention effects after 1 year. METHOD: The intervention consisted of (1) completing an online tool that generated feedback on the quality level of the health policy (9 scores) and (2) receiving advice (four contacts) from the local-regional support service for health promotion. In total 121 small-sized municipalities agreed to participate (intervention municipalities), and the nonparticipating municipalities (n = 46) were used as a comparison group. Chi-square tests were conducted to compare baseline quality scores between intervention and comparison municipalities and to assess the change (baseline to follow-up) within the intervention group. RESULTS: At baseline, intervention municipalities had significant higher health policy quality scores compared to the comparison municipalities. Municipalities interested in the intervention mostly had already high policy scores. A significant positive shift in the quality levels was found after 1 year in the intervention municipalities. CONCLUSION: The intervention succeeded in improving the quality levels of the local health policy, though municipalities scoring low and possibly benefiting most from the intervention need to be extra-motivated to participate.

Associations Between Objectively Assessed Components of Physical Activity and Health-Related Fitness in 10- to 14-Year-Old Children.

BACKGROUND: Our aim was to investigate the association between different components of physical activity (PA) and health-related fitness in 10-to 14-year-old children. METHODS: 241 children were recruited from 15 primary and 15 secondary schools. PA was assessed using the SenseWear Mini and an electronic diary. Health-related fitness was assessed using Eurofit and translated into indicators of body fatness, cardiorespiratory fitness and muscular fitness. Associations between PA intensity and physical fitness components were determined using multiple linear regression models adjusted for possible confounders and the contribution of PA domains per intensity categories was calculated. RESULTS: Associations between PA intensities and body fatness were low to moderate (|ß| = 0.09 to 0.44), explaining up to 6% of the variance in boys and 17% in girls. For cardiorespiratory fitness, associations were higher (|ß| = 0.17 to 0.56), with PA explaining up to 6% of the variance in boys and 31% in girls. Low-tomoderate associations (|ß| = 0.06 to 0.43) were found for muscular fitness, with PA explaining up to 7% in boys and 13% in girls. Stronger associations were found for sedentary and light activities. CONCLUSIONS: Low-to-moderate associations between PA and fitness components were observed, with higher associations in girls. Sedentary and light intensity activity showed the strongest link with body fatness, cardiorespiratory fitness and muscular fitness.

Age-related decline in muscle mass and muscle function in Flemish Caucasians: a 10-year follow-up.

Aging is a complex process that is accompanied with changes in both muscle mass and muscle function (strength and performance). Therefore, the current longitudinal study aimed to provide a better insight in 10-year aging-related changes in whole-body muscle mass and strength performance of the leg extensors during the adult life span. Data were gathered within the framework of the first- (2002-2004: baseline) and third-generation Flemish Policy Research Center Sport (2012-2014: follow-up). Results are based on muscle characteristics data of 591 Flemish Caucasian adults (19-73 years, 381 men). Skeletal muscle mass (SMM) was determined with bioelectrical impedance analysis. Biodex Medical System 3® dynamometer was used to measure isometric (PTstatic120°) and isokinetic (PTdynamic60° and PTdynamic240°) strength, ballistic movement speed (S 20 %), and muscular endurance (work) of the knee extensors. Overall strength performance was higher at both evaluation moments in men compared to women (p < 0.01). But only S 20 % declined significantly faster in men compared to women (p < 0.01). Age and baseline strength performance were negatively related with the change in strength performance, even when corrected for SMM, protein intake, and energy expenditure during sports (E sport). In conclusion, strength performance was not associated with E sport in this study, but protein intake was associated with isometric strength in men, and with ballistic and isokinetic strength in women. Changes in S 20 % were significantly greater in men compared to women. Baseline values of strength performance and age were associated with changes in strength performance parameters, even after correction for SMM, protein intake, and E sport.

Skeletal Maturation, Body Size, and Motor Coordination in Youth 11-14 Years.

PURPOSE: The objective of this study is to estimate the relative contribution of biological maturation to variance in the motor coordination (MC) among youth and to explore gender differences in the associations. METHODS: Skeletal maturation (Tanner-Whitehouse 3), stature, body mass, and MC (Körperkoordinationstest für Kinder) were assessed in 613 youths, 284 boys and 329 girls 11-14 yr of age. Standardized residuals of skeletal age on chronological age were used as the estimate of skeletal maturity status independent of chronological age. Hierarchical multiple regression analyses were used to analyse associations between skeletal maturity status and MC. RESULTS: Skeletal maturity status by itself, i.e., standardized residuals of skeletal age on chronological age (step 3) explained a maximum of 8.1% of the variance in MC in boys (ΔR3 in the range of 0.0%-8.1%) and 2.8% of the variance in girls (ΔR3 in the range of 0.0%-2.8%), after controlling for stature, body mass and interactions of the standardized residuals of skeletal age on chronological age with stature and body mass. Corresponding percentages for the interactions of the standardized residuals of skeletal age and stature and body mass, after adjusting for stature and body mass (step 2) were 8.7% in boys (ΔR2 in the range of 0.3%-8.7%) and 7.1% in girls (ΔR2 in the range of 0.1%-7.1%). Chow tests suggested structural changes in ß-coefficients in the four MC tests among boys and girls, 12-13 yr. CONCLUSION: The percentage of variance in the four MC tests explained by skeletal maturation was relatively small, but the relationships differed between boys and girls. By inference, other factors, e.g., neuromuscular maturation, specific instruction and practice, sport participation, and others may influence MC at these ages.

Change, stability and prediction of gross motor co-ordination in Portuguese children.

BACKGROUND: The knowledge about intra- and inter-individual variation can stimulate attempts at description, interpretation and prediction of motor co-ordination (MC). AIM: To analyse change, stability and prediction of motor co-ordination (MC) in children. SUBJECTS AND METHODS: A total of 158 children, 83 boys and 75 girls, aged 6, 7 and 8 years, were evaluated in 2006 and re-evaluated in 2012 at 12, 13 and 14 years of age. MC was assessed through the Kiphard-Schilling's body co-ordination test and growth, skeletal maturity, physical fitness, fundamental motor skills (FMS), physical activity and socioeconomic status (SES) were measured and/or estimated. RESULTS: Repeated-measures MANOVA indicated that there was a significant effect of group, sex and time on a linear combination of the MC tests. Univariate tests revealed that group 3 (8-14 years) scored significantly better than group 1 (6-12 years) in all MC tests and boys performed better than girls in hopping for height and moving sideways. Scores in MC were also higher at follow-up than at baseline. Inter-age correlations for MC were between 0.15-0.74. Childhood predictors of MC were growth, physical fitness, FMS, physical activity and SES. Biological maturation did not contribute to prediction of MC. CONCLUSION: MC seemed moderately stable from childhood through adolescence and, additionally, inter-individual predictors at adolescence were growth, FMS, physical fitness, physical activity and SES.